Good quality herb
"I've been taking this off and on for decades. Now that I am in my 60s, I take it (along with a couple of other things) regularly to keep my brain from turning to mush. I don't have any control studies or lab tests, but anecdotally speaking, gotu kola absolutely helps with my memory. If I take it regularly, I can recall the answer to the word puzzles I did the day before. If I fail to take it (travel or whatever reason), after about a week I can't recall yesterday's answers. As I said, anecdotal, but I believe it works."
